Cartilage

Cartilage

Cartilage is characterized by an extracellular matrix (ECM) enriched with glycosaminoglycans and proteoglycans, macromolecules that interact with collagen and elastic fibers.

Function:

* Allows the tissue to bear mechanical stresses without permanent distortion

* Support soft tissues

* A shock-absorbing and sliding area for joints

* Facilitates bone movements

* Development and growth of long bones both before and after birth

Cartilage consists of cells called chondrocytes and an extensive extracellular matrix composed of fibers and ground substance.

Chondrocytes synthesize and secrete the ECM

cells are located in matrix cavities called lacunae.

Collagen, hyaluronic acid, proteoglycans, and small amounts of several glycoproteins are the principal macromolecules present in all types of cartilage matrix.

3 forms of cartilage: each exhibiting variation in matrix composition. In the matrix of 1) hyaline cartilage, the most common form, type II collagen is the principal collagen type ex: cartilage in nose and costal cartilage

2) Elastic cartilage possesses, in addition to collagen type II, an abundance of elastic fibers within its matrix.Ex: cartilage in external ear and epiglottis

3) Fibrocartilage, present in regions of the body subjected to pulling forces, is characterized by a matrix containing a dense network of coarse type I collagen fibers. Ex: pubic symphysis and cartilage of intervertebral disc

The perichondrium is a sheath of dense connective tissue that surrounds cartilage in most places, forming an interface between the cartilage and the tissue supported by the cartilage.

The perichondrium harbors the vascular supply for the avascular cartilage and also contains nerves and lymphatic vessels.

Articular cartilage, which covers the surfaces of the bones in movable joints, is lack of perichondrium and is sustained by the diffusion of oxygen and nutrients from the synovial fluid.

Why cartilage...